In an electromagnetic wave transmission device which uses a sheet configured to transmit an electromagnetic wave (hereinafter, referred to as “electromagnetic wave transmission sheet”), instability of electromagnetic wave transmission due to the generation of a standing wave in the electromagnetic wave transmission sheet has been and still is considered to be a problem.
Patent Document 1 (Japanese Unexamined Patent Publication No. 2007-281678) discloses a technique in which a resistor or an electromagnetic wave absorber is disposed in the end portion of the electromagnetic wave transmission sheet to suppress reflection of an electromagnetic wave and to reduce a standing wave.
Patent Document 2 (Japanese Unexamined Patent Publication No. 2010-114696) describes an electromagnetic wave transmission sheet in which the length of a width in a vertical direction to the traveling direction of an electromagnetic wave to be transmitted is substantially equal to a natural number multiple of half the wavelength of the electromagnetic wave to be transmitted such that a resonant state is placed in the vertical direction. The electromagnetic wave transmission sheet includes an electromagnetic wave absorbing medium which reduces reflection in the traveling direction of the electromagnetic wave to be transmitted, and does not include an electromagnetic wave absorbing medium which reduces reflection in the vertical direction to the traveling direction of the electromagnetic wave to be transmitted.